1. Field of the Invention
Embodiments of the invention relate to a semiconductor device and method of manufacturing a semiconductor device.
2. Description of the Related Art
Conventionally, mainstream semiconductor devices employed as power devices use silicon (Si) as a semiconductor material. However, silicon carbide (SiC), which is a wide bandgap semiconductor having a wider bandgap than silicon, has thermal conductivity that is 3 times that of silicon, a critical electric field strength that is 10 times that of silicon, and an electron drift velocity that is 2 times that of silicon. Therefore, application of SiC in power devices capable of high temperature operation with low loss and a high dielectric breakdown voltage is being researched.
Even among SiC devices, in power-metal oxide semiconductor field effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBT), a nickel (Ni) silicide is generally used to obtain a surface-side ohmic contact with the substrate. A method of manufacturing such is as follows.
First, after a desired impurity layer is formed on a SiC substrate, a gate insulating film is formed, and a poly-silicon pattern is formed on the gate insulating film. Next, after an interlayer insulating film is formed on the poly-silicon, a site where a contact is necessary is opened by etching. Next, a Ni film is formed at a bottom of the contact hole and a Ni silicide is formed by performing rapid thermal processing.
When the Ni silicide is formed, the Ni film contacts the interlayer insulating film whereby during the rapid thermal processing, Ni permeates the interlayer insulating film and the insulating property decreases. Thus, there is a technique of preventing the contact of the Ni film and the interlayer insulating film by use of a liftoff process (for example, refer to Japanese Patent No. 4671314).